Added link to stan model and author list

Author: bbbales2

knitr/hmm-example/hmm-example.Rmd

@@ -1,6 +1,9 @@
 ---
 title: "HMM Example"
-output: html_document
+author: "Ben Bales, Charles Margossian"
+output:
+  html_document: default
+  pdf_document: default
 ---
 
 ```{r setup, include=FALSE}
@@ -182,6 +185,8 @@ model {
 }
 ```
 
+The complete model is available on Github: [hmm-example.stan](https://github.com/stan-dev/example-models/tree/master/knitr/hmm-example/hmm-example.stan).
+
 ```{r echo = TRUE, results = FALSE, message = FALSE}
 model = cmdstan_model("hmm-example.stan")
 fit = model$sample(data = list(N = N, y = y), parallel_chains = 4)